mcpmesh-local-api: the mcpmesh-local/1 seam (mcpmesh §6.1) — protocol types (always) plus,
behind the client feature, the family NDJSON codec + a no-iroh UnixStream client.
The client feature is the D-A extraction: a non-net mcpmesh-local/1 client (kb's
self-registration, the host shell) links this WITHOUT pulling iroh via mcpmesh-net.